Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Instabilities from the most recent storm are improving, but there are some lingering concerns for slabs to break up to several feet deep on the small-grained facet layer at the storm interface. The most concerning slopes are well-drifted from strong winds during the storm. Consider the extent of previous drifting and terrain consequences before riding in steep terrain. Warming temperatures today could produce small, natural wet loose avalanches from very steep, sunbaked terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2.5

    The Northwest Mountains picked up over 2 feet of snow accompanied by strong winds during the most recent storm that ended Monday.   The storm formed slabs up to several feet thick above small-grained facets that may keep instabilities lingering a few days longer than usual.  Be cautious of leeward terrain: slabs are larger and more cohesive on wind-loaded slopes.  Slabs are smaller and less common in wind-sheltered terrain.  Use small, steep slopes and/or stability tests to assess instabilities in the upper snowpack.  You can generally avoid the problem on slopes less than about 35 degrees.

    1/31: A trio of natural avalanches on Schuylkill Ridge.  This image highlights the dangerous size potential of avalanches in leeward terrain.

Avalanche Discussion

A few patterns are emerging after the storm helping to inform your backcountry decisions over the next few days.  Thank you for your observations which help us paint a more accurate picture of conditions.    

  • This was the first major storm this winter that didn't produce natural avalanches breaking on our early-season weak layers, suggesting an improving trend that matches our snowpack observations.  However, a skier triggered a large avalanche that broke near the ground on Wednesday near Taylor Reservoir.  Although this was outside of our forecast area, the snowpack depth and structure are similar to what you will find in the snow-deprived parts of the Southeast Mountains, from Mt. CB to Whetstone to lower Brush and lower Cement Creek.  That is why we are continuing to message the threat of avalanches breaking on deeply buried weak layers in our shallower zone.
  • Natural avalanche activity breaking in the upper snowpack was more frequent and larger on wind-loaded slopes near and above treeline  (up to D2.5 in the Northwest Mountains and up to D2 in the Southeast Mountains).  It's those same types of slopes that remain most concerning today because the consequences are more serious and instabilities are more likely to linger longer.  Almost all of the reported avalanches below treeline during the most recent storm were D1 to D1.5 in size.   That doesn't mean you can't get into trouble below treeline, but there are fewer instabilities and the size of avalanches breaking in the upper snowpack will generally be smaller.  If the snowpack is deeper than 5 feet, focus on terrain consequences below treeline in case you find a rare lingering instability in the upper snowpack.  
  • During the last couple of days, we've seen a few skier-triggered slides on sunnier aspects (Red Lady, Snodgrass). The Snodgrass slides appear to be remotely triggered and produced one of the outlier D2's below treeline. This unstable pattern matches our recent unstable pit results on faceted crusts that were buried earlier in January.  Those issues seem to be more common in the Southeast Mountains, where shallower snowpacks + stronger inversions produced weaker facets during our mid-January dry periods.  Crusts can sometimes help preserve facets or create a more pronounced hardness change in the snowpack which prolongs instabilities.  Instabilities on southerly aspects will be more concerning mid to late day after surface crusts thaw.  Regardless of what aspect you are on, it's worthwhile probing to make sure you're on a snowpack deeper than 5 feet (150 cm), and dig down a few feet to test the upper snowpack structure before riding in bigger or more consequential terrain.  

Keep those beacon skills dialed by joining CBAC and Irwin Guides Saturday, February 4th at the Slate River TH for free training. The 1-hour sessions will begin at 10, 11, and noon. No sign up necessary.

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